vc4: Emit resets of the uniform stream at the starts of blocks.

If a block might be entered from multiple locations, then the uniform
stream will (probably) be at different points, and we need to make sure
that it's pointing where we expect it to be.  The kernel also enforces
that any block reading a uniform resets uniforms, to prevent reading
outside of the uniform stream by using looping.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/gallium/drivers/vc4/vc4_qir.h b/src/gallium/drivers/vc4/vc4_qir.h
index e7ddfaa1fcb..88eda225d80 100644
--- a/src/gallium/drivers/vc4/vc4_qir.h
+++ b/src/gallium/drivers/vc4/vc4_qir.h
@@ -162,6 +162,12 @@ enum qop {
          * that block->successor[1] may be unset if the condition is ALWAYS.
          */
         QOP_BRANCH,
+
+        /* Emits an ADD from src[0] to src[1], where src[0] must be a
+         * QOP_LOAD_IMM result and src[1] is a QUNIFORM_UNIFORMS_ADDRESS,
+         * required by the kernel as part of its branch validation.
+         */
+        QOP_UNIFORMS_RESET,
 };
 
 struct queued_qpu_inst {
@@ -260,6 +266,11 @@ enum quniform_contents {
 
         QUNIFORM_ALPHA_REF,
         QUNIFORM_SAMPLE_MASK,
+
+        /* Placeholder uniform that will be updated by the kernel when used by
+         * an instruction writing to QPU_W_UNIFORMS_ADDRESS.
+         */
+        QUNIFORM_UNIFORMS_ADDRESS,
 };
 
 struct vc4_varying_slot {
@@ -521,6 +532,7 @@ struct qreg qir_uniform(struct vc4_compile *c,
                         uint32_t data);
 void qir_schedule_instructions(struct vc4_compile *c);
 void qir_reorder_uniforms(struct vc4_compile *c);
+void qir_emit_uniform_stream_resets(struct vc4_compile *c);
 
 struct qreg qir_emit_def(struct vc4_compile *c, struct qinst *inst);
 struct qinst *qir_emit_nondef(struct vc4_compile *c, struct qinst *inst);